Rare-earth element distribution in Archaean gneisses and anorthosites,Godthåb area,West Greenland |
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| Authors: | RK O&#x;Nions RJ Pankhurst |
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| Institution: | Department of Geology and Mineralogy, University of Oxford, Oxford Great Britain |
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| Abstract: | Rare-earth element (REE) distribution patterns have been determined for samples of Amîtsoq gneiss from the Godthåb and Isua areas. All have fractionated REE patterns with light REE enrichment, but some leucocratic components show extreme depletion in heavy REE. Various different crystal-liquid equilibria appear to have been involved in their petrogenesis. Fractional crystallization of garnet from a basic or intermediate magma, or partial melting of a basic or intermediate source with a high modal garnet content are considered as possible mechanisms for the generation of the leucocratic components. Anorthosites from Ameralik and Buksefjord show slight light REE enrichment with small or undetectable Eu anomalies, possibly due to crystallization under a high fO2. |
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